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ENDOCRINE AND DIABETES
Diabetes Biology (B.G.B., A.F., J.H.), Exploratory Biology (J.C.), Department of Pharmacokinetics, Dynamics, and Metabolism (N.H.), Structural and Computational Biology (P.A.R.), Pfizer Global Research and Development, La Jolla, California; Drug Metabolism/DMPK, Covance Laboratories, Madison, Wisconsin (F.T.); and Endocrinology, Division of Medical Sciences, University of Birmingham, Birmingham, United Kingdom (P.M.S.)
Glucocorticoids, through activation of the glucocorticoid receptor (GR), regulate hepatic gluconeogenesis. Elevated hepatic expression and activity of 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) play a key role in ligand-induced activation of the GR through the production of cortisol. Evidence from genetically modified mice suggests that inhibition of 11βHSD1 might be a therapeutic approach to treat the metabolic syndrome. We have identified a potent 11βHSD1 inhibitor, 4'-cyano-biphenyl-4-sulfonic acid (6-amino-pyridin-2-yl)-amide (PF-915275), that is selective for the primate and human enzymes. The objective of this study was to demonstrate target inhibition with PF-915275 and to quantify the relationship between target inhibition and drug exposure in monkeys. We characterized the ability of PF-915275 to inhibit the conversion of prednisone, a synthetic cortisone analog that can be distinguished from the endogenous substrate cortisone, enabling a direct measure of substrate to product conversion without the complication of feedback. Adult cynomolgus monkeys were administered either vehicle or various doses of PF-915275 followed by a 10-mg/kg dose of prednisone. Prednisone conversion to prednisolone and the concentrations of PF-915275 were measured by liquid chromatography/tandem mass spectrometry. PF-915275 dose-dependently inhibited 11βHSD1-mediated conversion of prednisone to prednisolone, with a maximum of 87% inhibition at a 3-mg/kg dose. An exposure-response relationship was demonstrated, with an estimated EC50 of 391 nM (total) and 17 nM (free). Insulin levels were also reduced in a dose-related manner. These results should enable the development of a biomarker for evaluating target modulation in humans that will aid in identifying 11βHSD1 inhibitors to treat diabetes and other related metabolic diseases.
Address correspondence to: Dr. B. Ganesh Bhat, Diabetes and Metabolism Pharmacology, Genomics Institute of the Novartis Foundation, 10675 John Jay Hopkins Dr., San Diego, CA 92121. E-mail: gbhat{at}gnf.org